The phenotype and gene frequencies of HLA class II alleles were studied in the North-eastern Thai population. Blood samples were collected from 100 unrelated healthy North-eastern Thais. The HLA-DRB1 and DQB1 genes were typed using the polymerase chain reaction--sequence specific primer (PCR-SSP) and polymerase chain reaction--sequence specific oligonucleotide probe (PCR-SSO) techniques. Twenty-six HLA-DRB1 and 11 DQB1 alleles were found in this population. DRB1*1202, 1502, 0405 and DQB1*0502/0504, 0301/0304 alleles were commonly found. Linkage disequilibrium analysis suggested the existence of 13 DR-DQ haplotypes. The DRB1*1502-DQB1*0501 haplotype was the most common. The DRB1*1106-DQB1*0301/0304 haplotype was found only in North-eastern Thais and not in other Thai populations. Comparative analysis of the HLA-DR/DQ alleles revealed differences in the distributions of these alleles amongst different ethnic groups. Interestingly, the distributions of HLA class II alleles in Central Thai, North-eastern Thai and Southern Chinese populations are similar. However, it appears that the distribution in the Central Thais is a mixture of those in Southern Chinese and North-eastern Thais, suggesting the existence of Thai-Chinese admixtures in the Central Thai population. This study provides basic information for further studies of the MHC in anthropology, organ transplantation and disease susceptibility in the North-eastern Thai population.

HPA-1a was found in 100 percent of Thais, which is the same frequency as in other Asian populations but somewhat different from that in whites (97.9%). Therefore, HPA-1a will not cause neonatal alloimmune thrombocytopenia or post-transfusion purpura in Thais. According to the frequencies of HPA-2b, HPA-3a, HPA-4a, HPA-4b, HPA-5b, and Naka antigens, they may induce neonatal alloimmune thrombocytopenia, posttransfusion purpura, and platelet refractoriness in Thais.

Background: Hepatitis C virus (HCV) infection is an important cause of liver cancer in Thailand. The highest prevalence of anti-HCV positive among Thai blood donors is found in the northeastern region. The present analysis of the genotype distribution among anti-HCV positive northeastern-Thai blood donors was conducted to provide a base for the epidemiological pattern of HCV infection in this region. Materials and Methods: A total of 112 HCV seropositive healthy blood donors were randomly selected and tested for the presence of HCV-RNA by RT-PCR. HCV-RNA positive samples were genotyped by direct sequencing at core region genomes and confirmed by phylogenetic analysis. Results: HCV viremia was found in 94.6% (106/112) of HCV seropositive blood donors. There were 3 major genotypes distributed among this population. HCV genotype 3a was the most prevalent (71.7%) followed by genotypes 1a (7.5%), 1b (7.5%), 6i (3.8%), 6f (2.8%) and 6n (1.9%). Conclusions: HCV genotype 3a in asymptomatic infections in northeastern Thailand is significantly higher than other previous reports. Subgenotype 6 prevalence is less than in neighboring countries and distribution patterns differ. The findings are relevant as predictors for using interferon therapy in this population.

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Blood group antigens can be distributed differently within different nationalities. Therefore, information about the prevalence of blood group antigens in the Lao population will be useful for providing better blood transfusion services in the Lao People's Democratic Republic. The purpose of this study was to determine the prevalence of blood group antigens in Lao blood donors. Blood samples from 464 Lao national volunteer blood donors were typed for antigens in various blood group systems including ABO, MNS, P1PK, Rh, Kell, Lewis, Duffy, Kidd, and Diego. The results show similar antigen prevalence to that among Northeast Thais for ABO, MNS, P1PK, Rh, Kell, and Duffy systems. In the ABO system, O was the highest at 37.72 percent, followed by 35.56 percent B, 19.83 percent A 1 , 6.47 percent A 1 B, and 0.43 percent A 2 B. The common phenotypes were D+C+E-c-e+ at 60.43 percent, M+N-S-s+ at 46.55 percent, Fy(a+b-) at 80.82 percent, Jk(a+b+) at 39.44 percent, and kk at 99.72 percent. Interestingly, Le(a-b-) was found at 50.43 percent, which was significantly higher than previous reports in Thais and Taiwanese. The P1 antigen was found in only 18.97 percent, which is much lower than in Whites and Blacks. Rare phenotypes were Fy(a-b+) and Jk(a-b-), found at 0.22 percent and 4.31 percent, respectively. In terms of negative antigens the study shows 0.22 percent Fy(a-), 35.34 percent Jk(a-), 29.53 percent Jk(b-), 3.04 percent C−, 2.39 percent e−, and 5.17 percent M−. The high prevalence of C, e, and Fy a and immunogenicity of these antigens may induce alloimmunization in transfusion-dependent patients, creating difficulties providing blood from Lao donors. The information obtained from this study will be useful for improving transfusion therapy in the country, especially for estimation of the availability of compatible blood for patients who have produced antibodies.